/* 大象 */
function Elephant(){

}



/* 冰箱 */
function Frige() {

}

Frige.prototype.openDoor = function () {

}

Frige.prototype.closeDoor = function () {

}

Frige.prototype.join = function(something){
    this.openDoor();
    //装东西

    this.closeDoor();
}



var frig = new Frige();
frig.join(new Elephant())
